A TFT-LCD (thin film transistor liquid crystal display) device is one of main types of flat display devices, and has become an important display device in modern IT and video products. A main driving principle of the TFT-LCD device is as follows. A system main board connects R/G/B compression signals, control signals and power to a connector on a PCB (printed circuit board) via wires; data is processed by a TCON (timing controller) IC (integrated circuit) on the PCB board, and then the data is connected to an active area via a S-COF (source-chip on film) and G-COFs (gate-chips on film) so as to enable an LCD device to obtain required power supply and signals, as shown in FIG. 1.
In actual development and detection of a product, it is prescribed that an EMI (electromagnetic interference) test should be carried out, which aims to prevent the product from causing bad effects to an article or a human body around it. An essence of the EMI test is to detect energy irradiated by the product in each frequency band. A maximum Swing (a maximum swing of a differential signal relative to a reference voltage) of mini-LVDS communicated between a TCON and an S-COF is strongly correlated to an EMI test result. The greater a swing value is, the higher energy of a frequency point is, and the worse the EMI result is. The smaller the swing value is, the better the EMI result is, but it may result in that the S-COF cannot read data correctly.